Can you build a dApp on Bitcoin?

First, there are no blockchains on Ethereum. What you have on Ethereum are tokens that leverage the Ethereum blockchain to offer services and products for users. There have been several efforts to create a completely programmable layer on Bitcoin. One of the most prominent attempts is Stacks which allows developers to build applications on the Bitcoin blockchain. Stacks uses clarity, a programming language known as clarity, and PoX or proof-of-extension consensus to enable the development of applications with in-build security on Bitcoin. You can watch an explanatory video and read more about this here.